zynq: Do not explicitely enable icache

icache is already enabled by default.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

board/xilinx/zynq/board.c

@@ -59,8 +59,6 @@ int board_init(void)
 	}
 #endif
 
-	icache_enable();
-
 #ifdef CONFIG_FPGA
 	fpga_init();
 	fpga_add(fpga_xilinx, &fpga);